Sunday, 7 January 2018

Are they antlers? Perhaps they are horns? They are definitely not antenna – the Serengeti is not (as far as we know) wired for giraffid telecommunications. They are called ossicones – and giraffes are born with them.

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This sounds as if it may cause problems to the mother giraffe (called a cow) when giving birth. However, they have a trick up their metaphorical sleeve. When a baby giraffe is born (and it’s called a calf), the ossicone is not attached to the skull and so is flexible – at least in terms of being pliable as the calf proceeds through the birth canal. Plus it is made of cartilage not living bone.

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The distinction is important. Cartilage is the padding, rather like rubber, that protects the ends of long bones. We have cartilage around many of the components which make up our body including the ear and the nose. As such, cartilage is much less flexible than muscle but on the other hand is nowhere near as rigid or as hard as bone. However, the ossicone does turn in to bony tissue as the giraffe grows and reaches maturity. In fact the process begins a week after birth. The term for this is ossify – and that’s how these strange cone-like protuberances get their name.

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The ossicone is almost always covered by fur. Sometimes, however, adult males will wear this down. As the male giraffe (the bull) gets older the ossicone fuses to the skull – it will have its uses.

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For fighting. There are times when an adult male must fend off a competitor. This is often settled quickly, with a few blows to the opponent’s neck. However, sometimes things can get a lot more heated. Rivals are not tolerated and when this happens there is a lot of pushing and shoving. If there is an impasse, instead of aiming for the neck they aim for the rump of the legs. Take a look at this fascinating footage showing the sheer devastation that a fight between two mature males can wreak.

There simply have not been enough studies done on this part of the fossil record to ascertain whether ossicones evolved independently. Certainly the base from which a deer’s antlers grow is similar to an ossicone. Many scientists believe that, as the evolutionary ancestors of giraffes had antlers, that the ossicones served as a support structure for them.

Can you imagine the damage that could be done if giraffes had antlers?

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So why might the antlers have disappeared? As you have seen in the video, the adult males fight by almost wrapping their long necks around each other. Thinner necks would have meant that frontal assaults using antlers would have resulted in way too many fatalities. It’s a joust, after all – and not a fight to the death. So as the necks grew longer, the need for antlers was rendered useless. This is, of course, speculation but it seems like a practical reason for the antlers to eventually disappear leaving just the residual ossicone.

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The verdict is out on this one and only time – and much more scientific research – will tell whether the ossicone is an evolutionary left-over or that they serve another function as yet unknown.

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